(AP/Dave Martin)If there's one thing that should unite those who support the death penalty and those who don't, it's a desire to make sure no one is executed for a crime he didn't commit.

And if there's one thing that ought to preoccupy our justice system, it's making sure such a terrible travesty does not occur.

Unfortunately, that's not the case. A ruling last week by the Alabama Court of Criminal Appeals offers a timely example. The court strains at a gnat in Anthony Ray Hinton's appeal, but blithely swallows a camel -- that is, it overlooks strong evidence that Hinton did not actually commit the deadly restaurant robberies that landed him on Death Row.

Hinton was convicted in 1986 of the Birmingham-area crimes, which left two managers dead and another injured. The appeals court decision last week focused on the very narrow question of whether a man hired by Hinton's original defense lawyer to challenge crucial ballistics evidence was, in fact, an expert on guns.

The criminal appeals court concluded Andrew Payne was expert enough. "Although he had not spent his entire career engaged in firearms identification, as did the state's expert witnesses, Payne clearly possessed knowledge of gun barrels, rifling characteristics, and toolmarks beyond that of an average layperson," the judges ruled.

That effectively knocks out one of Hinton's arguments: His lawyer failed him by not hiring someone more qualified to dispute the state of Alabama's claim that crime scene bullets matched a .38 special found at Hinton's mother's home. This was the only physical evidence linking Hinton to the crimes, and prosecutors admit there would have been no case without it.

Payne testified at Hinton's initial criminal trial that the state's conclusions about the bullets and guns were wrong. But his expertise and findings were attacked harshly and successfully by prosecutors during cross-examination. Among other things, he admitted he never test-fired Hinton's gun, didn't know how to turn on the state Department of Forensic Sciences' microscope, and had only one eye.

Defense lawyers at the time said they couldn't afford anyone better to challenge the gun evidence. But Hinton's current legal team has since found nationally known experts who reached the same verdict as Payne.

And here's where you might see a camel starting to take shape.

The new ballistics experts -- one of them the former chief of the FBI's firearm and toolmark identification unit -- have said the bullets from the crime scenes couldn't be matched to a single gun, much less to Hinton's. They said Hinton's weapon was mechanically incapable of firing the bullets recovered in one of the crimes.

Then, there's this: On the night of one of the robberies, Hinton was clocked in and working at a Bruno's warehouse in Ensley, 15 miles away from the scene of the crime. For the timeline to work, Hinton had to sneak away from work, drive to a restaurant in Bessemer, follow victim Sidney Smotherman to a nearby Food World, wait for Smotherman to shop and check out at 12:26 a.m., fall in behind him again, bump his car, rob him, shoot him and drive 15 miles back to Ensley in time to be seen by a supervisor at 12:40 a.m.

Those are some big humps to get over if you're going to conclude Hinton is guilty. But not so big, apparently, that they couldn't slide down the criminal appeals court's gullet.

In the appeals court's defense, it focused only on the issue of Payne's expertise at the direction of the Alabama Supreme Court. But that was only after the Court of Criminal Appeals had disregarded the overriding concerns about Hinton's guilt in the first place. The Court of Criminal Appeals swallowed the camels and the gnats in upholding Hinton's conviction on a 3-2 vote in 2006. The Supreme Court, we suppose, at least found a gnat.

This is an alarming reminder about the truth about the death penalty. People complain about the appeals afforded those sentenced to death, about the legal technicalities that sometimes result in new trials, and about the emphasis on defendants' rights. But for all those restraints, there is no fail-safe mechanism in Alabama that kicks in to ensure innocent people are not convicted and put to death.

In our view, this is the most forceful argument of all for why Alabama needs to abandon the death penalty altogether. The state cannot afford to be so careless in inflicting a punishment that cannot be undone.

And really, the holes in the appeal system are not limited to Alabama, as shown by a book that examined the first 250 cases across the country in which people were cleared by DNA evidence after being convicted of crimes, including some that led to death sentences. The book found that 87 percent of all the convictions were upheld during the regular appeals process. In 10 percent of the cases, appeals courts actually cited the "overwhelming" evidence against people who, we now know, were not guilty at all.

The book "Convicting the Innocent: Where Criminal Prosecutions Go Wrong" also found a number of common threads in those cases that led to erroneous verdicts. In 74 percent of the cases, faulty forensic evidence -- such as ballistics reports -- played a role.

Alas, if Hinton is innocent, there is no DNA evidence to test. There are just plenty of gnats, and maybe a camel.